Methods of making an antistatic agent

ABSTRACT

A method for making the phosphonium sulfonate salt of generic formula (1):  
                 
 
wherein each X is independently a halogen or hydrogen, provided that the molar ratio of halogen to hydrogen is greater than about 0.90; p is 0 or 1 and q and r are integers of 0 to about 7 provided that q+r is less than 8 and that if p is not zero then r is greater than zero; and each R is the same or different hydrocarbon radical containing 1 to about 18 carbon atoms, the method comprising combining in an aqueous medium a compound of generic formula (2):  
                 
wherein M is Li or Na, and X, q, p, and r are as defined above, with a stoichiometric excess of a compound of the generic formula (3): 
 
(R) 4 P-Z  (3) 
wherein Z is a halogen and R is as defined above; and separating the product of formula (1) from the medium.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application Ser.No. 60/562,010, filed Apr. 13, 2004, which is incorporated by referenceherein in its entirety.

BACKGROUND OF THE INVENTION

This disclosure relates to a method of making an antistatic agent.

Thermoplastics are useful in the manufacture of articles and componentsfor a wide range of applications, from automotive parts to electronicappliances. Because of their broad use, particularly in electronicapplications, it is desirable to provide thermoplastic resins withantistatic agents. Many polymers or blends of polymers are relativelynon-conductive, which can lead to static charge build-up duringprocessing and use of the polymer. Charged molded parts, for example,may attract small dust particles, and may thus interfere with a smoothsurface appearance, for example by causing a decrease in thetransparency of the article. In addition, the electrostatic charge maybe a serious obstacle in the production process of such polymers.

Anti-static agents are materials that are added to polymers to reducetheir tendency to acquire an electrostatic charge, or, when a charge ispresent, to promote the dissipation of such a charge. Organicanti-static agents are usually hydrophilic or ionic in nature. Whenpresent on the surface of polymeric materials, they facilitate thetransfer of electrons and thus eliminate the build up of a staticcharge. Anti-static agents have also been added to the polymercomposition before further processing into articles, and may thus bereferred to as “internally applied.” Useful anti-static agents appliedin this manner are thermally stable and able to migrate to the surfaceduring processing.

A large number of anti-static agents having surfactants as their mainconstituent have been considered and tried. Many suffer from one or moredrawbacks, such as lack of compatibility with the polymer (whichinterferes with uniform dispersibility), poor heat stability, and/orpoor antistatic characteristics. Poor heat resistance in particular canadversely affect the optical properties of engineering thermoplasticssuch as aromatic polycarbonates.

Particular phosphonium salts of certain sulfonic acids, however, havebeen shown to be useful antistatic agents. U.S. Pat. No. 4,943,380discloses reducing the static charge on polycarbonate resins with ananti-static composition containing 90-99.9 weight % of polycarbonate and0.1-10 weight % of a heat resistant phosphonium sulfonate having thegeneral formula:

wherein R is a straight or branched chain alkyl group having 1 to 18carbon atoms; R₁, R₂ and R₃ are the same, each being an aliphatichydrocarbon having 1 to 8 carbon atoms or an aromatic hydrocarbon grouphaving 6 to 12 carbon atoms; and R₄ is a hydrocarbon group having 1 to18 carbon atoms.

U.S. Pat. No. 6,194,497 discloses antistatic resin compositions,particularly transparent resin compositions, comprising a thermoplasticpolymer and a halogenated medium- or short-chain alkylsulfonic acid saltof a tetrasubstituted phosphonium cation. The antistatic agent describedtherein is prepared by ion exchange of a potassium haloalkylsulfonate toproduce the corresponding acid. The haloalkylsulfonic acid is thenreacted with tetrabutylphosphonium hydroxide to product the antistaticagent.

An advantage of this synthesis is that use of an ion exchange stepduring synthesis results in a product that is very pure, i.e., containslittle to no halogenated compounds that may ultimately lead todegradation of resins such as polycarbonates. However, while suitablefor its intended purposes, this particular synthesis also has a numberof drawbacks. For example, use of an ion exchange step increases theexpense of the process, and may lead to the production of wasterequiring disposal procedures. The synthesis also uses the potassiumsalt as a starting product, which is prepared from the correspondingsulfonylfluoride. Since the solubility of potassium peralkylsulfonatesis relatively low, e.g., on the order of 5% at 20° C., a water/ethanolmixture is needed in the ion exchange. The flammability of ethanolrequires the implementation of significant safety precautions during thesynthesis. In addition, selecting the appropriate water/ethanol ratio isalso important. An excess of alcohol may render the final productsoluble in the reaction solvent, such that isolation of the product mayrequire a further extraction step.

There accordingly remains a demand in the art for more efficientprocesses, particularly one-step processes, for making phosphoniumsulfonate antistatic agents, as well as thermoplastic resin compositionsthat incorporate these antistatic agents. It would further be desirablefor such processes to produce the antistatic agent in good yieldswithout having a detrimental effect on the safety of the process and/orthe purity of the product.

BRIEF SUMMARY OF THE INVENTION

The above-described and other deficiencies of the art are met by amethod of making a phosphonium sulfonate salt of formula (1):

wherein each X is independently a halogen or hydrogen, provided that themolar ratio of halogen to hydrogen is greater than about 0.90; p is 0 or1 and q and r are integers of 0 to about 7, provided that q+r is lessthan 8 and that if p is not zero then r is greater than zero; and each Ris independently a hydrocarbon radical having 1 to about 18 carbonatoms, the method comprising combining in an aqueous medium a compoundof the formula (2):

wherein M is Li or Na, and X, q, p, and r are as defined above, with acompound of the formula (3):(R)₄P-Z  (3)wherein Z is a halogen and R is as defined above; and separating theproduct of formula (1) from the aqueous medium.

In another embodiment, a method of making the phosphonium sulfonate saltof formula (1) comprises first combining in an aqueous medium, acompound of the formula (4)

with a stoichiometric excess of a compound of the generic formula (5):(R)₄P—OH  (5)wherein X, p, q, r, and R have the same meanings as in formula (1); andseparating the product of formula (1) from the aqueous medium.

In another embodiment, a method of making the phosphonium sulfonate saltof formula (1) comprises combining in an aqueous medium sodium hydroxideand/or lithium hydroxide, a compound of the generic formula (4) above,and a compound of the generic formula (3) above, wherein X, q, p, r, andR are as defined above; and separating the phosphonium sulfonate offormula (1) from the aqueous medium.

Another embodiment comprises an antistatic agent of formula (1) made byone of the foregoing methods.

In another embodiment there are provided thermoplastic compositionscomprising a thermoplastic polymer and an antistatic agent made by oneof the foregoing methods.

DETAILED DESCRIPTION OF THE INVENTION

It has been unexpectedly found by the inventors hereof that aphosphonium haloalkylsulfonate salt suitable for use as antistatic agentmay be readily obtained in aqueous medium in one step from thecorresponding tetraalkylphosphonium halide and lithium or sodiumhaloalkylsulfonate salt. Alternatively, the phosphoniumhaloalkylsulfonate salt may be obtained in aqueous medium in one stepfrom the corresponding tetraalkylphosphonium halide or hydroxide and thehaloalkylsulfonyl fluoride. The reactants are readily available, and useof water as the reaction solvent expedites isolation of the product.Thus, in a surprising and highly advantageous feature, the inventorshereof have found that a simple mixing of the reactants may result in aprecipitation of the targeted anti-static molecule in high yields.

In general, the phosphonium haloalkylsulfonate salts are of the genericformula (1):

wherein X is independently selected from halogen or hydrogen, providedthat the molar ratio of halogen to hydrogen is greater than about 0.90.The halogens may be independently selected from bromine, chlorine,fluorine, and iodine. Specifically, the halogen is fluorine.

Further in formula (1), p is zero or one, and q and r are integers of 0to about 7, provided that q+r is less than 8 and that if p is not zerothen r is greater than zero. In one embodiment, p is zero.

Each R in formula (1) is independently a hydrocarbon radical containing1 to about 18 carbon atoms, that is, each R is the same or different,and may be a straight or branched chain aliphatic hydrocarbon radicalcontaining 1 to about 18 carbon atoms, or an aromatic hydrocarbonradical containing 6 to about 18 carbon atoms. As used herein, an“aromatic” radical is inclusive of fully aromatic radicals, aralkylradicals, and alkaryl radicals. In one embodiment, three of the R groupsin the organic phosphonium cation may be the same aliphatic hydrocarbonradical containing 1 to about 8 carbon atoms or aromatic hydrocarbonradical containing 6 to about 12 carbon atoms, while the fourth R groupmay be a hydrocarbon radical containing 1 to about 18 carbon atoms.

The antistatic agent may thus be a highly halogenated phosphoniumsulfonate salt containing an organic sulfonate anion and atetrasubstituted organic phosphonium cation. Specific examples areperfluorinated salts, but due to the production method of thefluorination (electrolysis) sometimes only partly fluorinated compoundsare formed.

Specific examples of suitable organic sulfonate anions includeperfluoromethane sulfonate, perfluoroethane sulfonate, perfluoropropanesulfonate, perfluorobutane sulfonate, perfluoropentane sulfonate,perfluorohexane sulfonate, perfluoroheptane sulfonate, andperfluorooctane sulfonate. Combinations of the foregoing may also bepresent.

Examples of specific phosphonium cations include cations such astetramethyl phosphonium, tetraethyl phosphonium, tetra-n-propylphosphonium, tetraisopropyl phosphonium, tetrabutyl phosphonium,triethylmethyl phosphonium, tributylmethyl phosphonium, tributylethylphosphonium, trioctylmethyl phosphonium, trimethylbutyl phosphonium,trimethyloctyl phosphonium, trimethyllauryl phosphonium,trimethylstearyl phosphonium, triethyloctyl phosphonium, tetraphenylphosphonium, triphenylmethyl phosphonium, triphenylbenzyl phosphonium,and tributylbenzyl phosphonium. Combinations of the foregoing may alsobe present.

In one embodiment there is provided a method for making the phosphoniumsulfonates of formula (1) comprising combining, in an aqueous medium, acompound of the formula (2):

wherein M is an alkali metal selected from lithium (Li) or sodium (Na),and X, q, p, and r are as defined above, with a stoichiometric excess ofa compound of the formula (3):(R)₄P-Z  (3)wherein Z is a halogen and R is as defined above; and separating theproduct of formula (1). Specifically Z may be bromine or chlorine.

In one manner of proceeding, the process may comprise dissolving aperhaloalkylsulfonate sodium or lithium salt of formula (2) in anaqueous medium. The aqueous medium may be substantially free of acosolvent such as ethanol, for example. As used herein, “an aqueousmedium” means a solution, dispersion, or suspension in water. Further asused herein, an aqueous medium “substantially free of a cosolvent” meansan aqueous medium containing less than about 1, specifically less thanabout 0.5, and more specifically less than about 0.1 volume percentcosolvent. While the use of a cosolvent is possible, and necessary inthe case of the potassium salts, the use of water substantially free ofa cosolvent results in a higher purity product, and avoids the safetyconcerns that arise from use of volatile solvents. Suitable cosolvents,when used, aid in dissolving the sulfonate alkali salts, and includelower alcohols such as methanol, ethanol, and the like, and chlorinatedsolvents such as dichloromethane, and the like. Mixtures of cosolventsmay be used.

The aqueous medium containing the perhaloalkylsulfonate alkali salt maythen be reacted with a tetrasubstituted phosphonium halide. The order ofaddition does not appear to be important, i.e., reaction may also beaccomplished by, for example, dissolving the tetrasubstitutedphosphonium halide in an aqueous medium and then adding theperhaloalkylsulfonate alkali salt; by simultaneously dissolving andmixing the reactants; by separately dissolving then mixing thereactants; or the like. The phosphonium sulfonate salts obtained hereinmay be obtained by using mixtures of perhaloalkylsulfonate alkali saltsand tetrasubstituted phosphonium halides.

The processes may be conducted at a broad range of temperatures andreaction times, and will depend on the particular reactants used,cosolvent (if present), desired yields, desired purity, cost,convenience, ease of manufacture, and like considerations. For example,temperatures for the various processes may generally be about 10° C. toabout 100° C., specifically about 20° C. to about 95° C., morespecifically about 30° to about 90° C. In one embodiment, the reactionis conducted at room temperature or ambient temperature, which maygenerally be about 20° C. to about 25° C. Likewise, reaction times mayvary, but generally may be about 5 minutes to about one day,specifically about 30 minutes to about 12 hours, or more specificallyabout 60 minutes to about 4 hours. These temperatures and times may bevaried greatly and may be determined by those of ordinary skill in theart.

The tetrasubstituted phosphonium halide may used in an at leastequimolar amount relative to the perhaloalkylsulfonate salt, and morespecifically, the molar ratio of the perhaloalkylsulfonate salt offormula (2) to the tetrasubstituted phosphonium halide of formula (3)may be about 1:1.001 to about 1:1.5, specifically about 1:1.002 to about1:1.1, more specifically about 1:1.005 to about 1:1.015. The optimumratio may vary depending on the particular reactants, temperature,cosolvent(s) (if present), and time, and is readily determined by one ofordinary skill in the art.

In another embodiment, the molar ratio of the perhaloalkylsulfonate saltof formula (2) to the tetrasubstituted phosphonium halide of formula (3)may be about 1.001:1 to about 1.5:1, specifically about 1.002:1 to about1.1:1, more specifically about 1.005:1 to about 1.015:1. The optimumratio may vary depending on the particular reactants, temperature,cosolvent(s) (if present), and time, and is readily determined by one ofordinary skill in the art.

In a highly advantageous feature, the reactants and aqueous medium areselected so that phosphonium sulfonate salt (1) precipitates from theaqueous medium at high purity, and may be isolated from impurities, inparticular halogen-containing impurities, by simple filtration andwashing. It is desirable to remove halogen-containing impurities inparticular (such as the tetrasubstituted phosphonium bromide and/orchloride) since these impurities are known to degrade resins such aspolycarbonate. Removal of the impurities is readily and efficientlyaccomplished by washing with water, since the impurities are soluble inwater, while the desired product is not.

In another embodiment there is provided a method for making thephosphonium sulfonate of formula (1) comprising combining in an aqueousmedium a sulfonylfluoride of the generic formula (4):

wherein X, p, q, and r have the same meanings as above, with astoichiometric excess of a tetrasubstituted phosphonium hydroxide of theformula (5):(R)₄P—OH  (5)wherein R is as defined above; and separating the product of formula (1)from the aqueous medium. In one embodiment, the reactants and aqueousmedium are selected so that phosphonium sulfonate salt precipitates fromthe aqueous medium.

In this embodiment the phosphonium sulfonate salt of formula (1) may beproduced in a one-step process, which may comprise reactingsulfonylfluoride (4) with tetrasubstituted phosphonium hydroxide (5) ina single vessel in an aqueous medium. Thus, compound (4) may bedispersed or dissolved in an aqueous medium containing a cosolvent orsubstantially free of a cosolvent such as is described above, to which atetrasubstituted phosphonium hydroxide (5) is then added. The order ofaddition does not appear to be important, i.e., reaction may also beaccomplished by, for example, dissolving the tetrasubstitutedphosphonium hydroxide (5) in an aqueous medium and then adding thesulfonylfluoride (4), or by simultaneously dissolving/dispersing andmixing the reactants. Combinations of different sulfonylfluorides (4)and/or different tetrasubstituted phosphonium hydroxide (5) may bereacted.

As above, a broad range of reaction times, temperatures and otherprocess conditions may be used, but room temperature is preferred forease of manufacture. Generally the tetrasubstituted phosphoniumhydroxide (5) is used in an amount of at least about 2 moles per mole ofsulfonylfluoride (4), and more specifically, the molar ratio of thecompound of formula (4) to the phosphonium hydroxide of formula (5) maybe about 1:2.01 to about 1:3, specifically about 1:2.1 to about 1:2.7,or more specifically of about 1:2.2 to about 1:2.6. The optimum ratiomay vary depending on the particular reactants, temperature,cosolvent(s) (if present) and time, and is readily determined by one ofordinary skill in the art.

In another embodiment there is provided a method for making thephosphonium sulfonate salts of formula (1) comprising combining, in anaqueous medium, a sulfonylfluoride of formula (4), a tetrasubstitutedphosphonium halide of formula (3), and an alkali metal or alkaline earthmetal base; and separating the phosphonium sulfonate of formula (1) fromthe aqueous medium. Suitable bases include, for example, alkalinehydroxides such as potassium hydroxide, sodium hydroxide, lithiumhydroxide, magnesium hydroxide, and the like. Mixtures may also be used.Potassium hydroxide, sodium hydroxide, and/or lithium hydroxide arepreferred. In one embodiment, the reactants and aqueous medium areselected so that phosphonium sulfonate salt precipitates from theaqueous medium.

Again, the order of addition does not appear to be important. Thus, thecomponents may be mixed simultaneously, or tetrasubstituted phosphoniumhalide (3) may be added to an aqueous solution/dispersion of the base,and this medium/dispersion added to a solution/dispersion of sulfonylfluoride (4). In still another embodiment, sulfonylfluoride (4) and thebase are combined, and allowed to react for a time effective to form thealkali sulfonate salt (2). Phosphonium halide (3) is then added to themedium to form the product without isolation of alkali sulfonate salt(2). This method is simple, efficient, and minimizes time and materials.Alternatively, alkali sulfonate salt (2) may be isolated and redissolvedwith or without cosolvent prior to addition of phosphonium halide (3).

A broad range of reaction times, temperatures, and other processconditions may be used, but about 25° C. (room temperature) to about100° C. is preferred for ease of manufacture. Optimal reactant ratiosare readily determined by one of ordinary skill in the art, and may be,for example, those described above.

Phosphonium sulfonate salt that may be made by the processes describedherein include those having the general formula (6):

wherein F is fluorine; n is an integer of 0 to about 7, S is sulfur; andeach R is the same or different aliphatic hydrocarbon radical containing1 to about 18 carbon atoms or an aromatic hydrocarbon radical containing6 to about 18 carbon atoms. In one embodiment, three of the R groups inthe organic phosphonium cation may be the same aliphatic hydrocarbonradical containing 1 to about 8 carbon atoms or aromatic hydrocarbonradical containing 6 to about 12 carbon atoms, while the fourth R groupmay be a hydrocarbon radical containing 1 to about 18 carbon atoms.Anti-static compositions comprising fluorinated phosphonium sulfonatesof formula (6) as the principle component thereof may be used in manydifferent ways to make use of their anti-static, compatibility and heatresistance characteristics, for example, in providing such anti-staticcharacteristics to thermoplastic resins. Suitable thermoplastic resinsinclude but are not limited to polycarbonate, polyetherimide, polyester,polyphenylene ether/polystyrene blends, polyamides, polyketones,acrylonitrile-butadiene-styrenes (ABS), or combinations comprising atleast one of the foregoing polymers. The phosphonium sulfonate salts arelow melting semi-solid materials, and as such, they may be handled as amolten liquid. Some embodiments of the present disclosure are solidcrystalline materials at room temperature (about 15 to about 25° C.) andare easy to weigh, handle, and add to the above-described thermoplasticresins.

In addition to the thermoplastic resin, the thermoplastic compositionmay include various additives ordinarily incorporated in resincompositions of this type. Mixtures of additives may be used. Suchadditives may be mixed at a suitable time during the mixing of thecomponents for forming the composition. Examples of suitable additivesare impact modifiers, fillers, heat stabilizers, antioxidants, lightstabilizers, plasticizers, mold release agents, UV absorbers,lubricants, pigments, dyes, colorants, blowing agents, antidrip agents,and flame-retardants.

A common way to practice this method is to add the agent directly to thethermoplastic resin and to mix it at the time of polymer production orfabrication. It may be processed by traditional means, includingextrusion, injection, molding, compression molding or casting. Thethermoplastic compositions may be manufactured by methods generallyavailable in the art, for example, in one embodiment, in one manner ofproceeding, powdered thermoplastic resin, antistatic agent, and/or otheroptional components are first blended, optionally with chopped glassstrands or other fillers in a Henschel high speed mixer. Other low shearprocesses including but not limited to hand mixing may also accomplishthis blending. The blend is then fed into the throat of a twin-screwextruder via a hopper. Alternatively, one or more of the components maybe incorporated into the composition by feeding directly into theextruder at the throat and/or downstream through a sidestuffer. Suchadditives may also be compounded into a masterbatch with a desiredpolymeric resin and fed into the extruder. The extruder is generallyoperated at a temperature higher than that necessary to cause thecomposition to flow. The extrudate is immediately quenched in a waterbath and pelletized. The pellets, so prepared, when cutting theextrudate may be one-fourth inch long or less as desired. Such pelletsmay be used for subsequent molding, shaping, or forming.

The quantity of the phosphonium sulfonate salt added to thermoplasticresin is an amount effective to reduce or eliminate a static charge andmay be varied over a range. It has been found that if too little of theanti-static substituted phosphonium sulfonate salt is added to theresin, there still may be a tendency for static charge to build up on anarticle made of the resin. If the loadings of the anti-static additivebecome too high, the addition of these quantities is uneconomical, andat some level it may begin adversely to affect other properties of theresin. Thermoplastic compositions with enhanced antistatic propertiesmay be obtained using about 0.01 to about 10 weight percent (wt %),specifically about 0.2 to about 2.0 wt %, more specifically about 0.5 toabout 1.5 wt of the anti-static agent with about 90 to about 99.99 wt %,specifically about 99 to about 99.8 wt %, more specifically about 98.5to about 99.5 wt % polymer, based on the total weight of anti-staticagent and polymer. In one embodiment, in order to obtain a favorableresult by such an internal application method in transparentpolycarbonate grades, the antistatic agent is used generally in amountsof about 0.01 to about 3.0, specifically about 0.1 to about 1.5 weightpercent (wt. %) with respect to the molding composition or specificallyin amounts of about 0.4 to about 0.8 wt. %. The antistatic agentsprovided herein are more strongly resistant against heat and may beadded in lower quantities than the traditional ionic surfactants, e.g.phosphonium alkyl sulfonates, and the resin compositions have goodtransparency and mechanical properties.

The above-described phosphonium salts may further be used to preparethermoplastic polymer compositions having improved heat stability. Inone embodiment a polycarbonate composition comprising an antistaticagent manufactured by one of the above processes has a Yellowness Indexof less than about 15, specifically less than about 10, morespecifically less than about 8, and even more specifically less thanabout 6 after aging at 130° C. for 936 hours.

The thermoplastic composition comprising the antistatic agent may beused to form articles such as, for example, computer and businessmachine housings such as housings for monitors, handheld electronicdevice housings such as housings for cell phones, electrical connectors,and components of lighting fixtures, ornaments, home appliances, roofs,greenhouses, sun rooms, swimming pool enclosures, carrier tapes forsemiconductor package material, automobile parts, and the like.

The thermoplastic compositions may be converted to articles usingprocesses such as film and sheet extrusion, injection molding,gas-assist injection molding, extrusion molding, compression molding,and blow molding. Film and sheet extrusion processes may include and arenot limited to melt casting, blown film extrusion and calendaring.Co-extrusion and lamination processes may be used to form compositemulti-layer films or sheets. Single or multiple layers of coatings mayfurther be applied to the single or multi-layer substrates to impartadditional properties such as scratch resistance, ultra violet lightresistance, aesthetic appeal, and the like. Coatings may be appliedthrough application techniques such as rolling, spraying, dipping,brushing, or flow coating. Films or sheets may alternatively be preparedby casting a solution or suspension of the thermoplastic composition ina suitable solvent onto a substrate, belt, or roll followed by removalof the solvent.

Oriented films may be prepared through blown film extrusion or bystretching cast or calendared films in the vicinity of the thermaldeformation temperature using conventional stretching techniques. Forinstance, a radial stretching pantograph may be employed for multi-axialsimultaneous stretching; an x-y direction stretching pantograph can beused to simultaneously or sequentially stretch in the planar x-ydirections. Equipment with sequential uniaxial stretching sections canalso be used to achieve uniaxial and biaxial stretching, such as amachine equipped with a section of differential speed rolls forstretching in the machine direction and a tenter frame section forstretching in the transverse direction.

The thermoplastic compositions of the invention may also be converted toa multiwall sheet comprising a first sheet having a first side and asecond side, wherein the first sheet comprises a thermoplastic polymer,and wherein the first side of the first sheet is disposed upon a firstside of a plurality of ribs; and a second sheet having a first side anda second side, wherein the second sheet comprises a thermoplasticpolymer, wherein the first side of the second sheet is disposed upon asecond side of the plurality of ribs, and wherein the first side of theplurality of ribs is opposed to the second side of the plurality ofribs.

The films and sheets described above may further be thermoplasticallyprocessed into shaped articles via forming and molding processesincluding, for example thermoforming, vacuum forming, pressure forming,injection molding, and compression molding. Multi-layered shapedarticles may also be formed by injection molding a thermoplastic resinonto a single or multi-layer film or sheet substrate, for example byproviding a single or multi-layer thermoplastic substrate havingoptionally one or more colors on the surface, for instance, using screenprinting or a transfer dye; conforming the substrate to a moldconfiguration such as by forming and trimming a substrate into a threedimensional shape and fitting the substrate into a mold having a surfacewhich matches the three dimensional shape of the substrate; injecting athermoplastic resin into the mold cavity behind the substrate to (i)produce a one-piece permanently bonded three-dimensional product or (ii)transfer a pattern or aesthetic effect from a printed substrate to theinjected resin and remove the printed substrate, thus imparting theaesthetic effect to the molded resin.

Those skilled in the art will also appreciate that known curing andsurface modification processes, including but not limited toheat-setting, texturing, embossing, corona treatment, flame treatment,plasma treatment, and/or vacuum deposition may further be applied to theabove articles to alter surface appearances and impart additionalfunctionalities to the articles.

Accordingly, another embodiment of the invention relates to articles,sheets, and films prepared from the above thermoplastic compositions.

The above processes may be used to form phosphonium salts (1) in anexpedited manner and in high purity. In one embodiment, the total amountof ionic impurities is less than about 650 parts per million (ppm), morespecifically less than about 500 ppm, even more specifically less thanabout 100 ppm, more specifically less than about 50 ppm, and mostspecifically less than about 10 ppm. In another embodiment, the productscontain less than about 5 ppm of alkali metals, preferably less thanabout 4 ppm of alkali metals. In another embodiment, the productscontain less than about 500 ppm, preferably less than about 100 ppm,more preferably less than about 50 ppm, and most preferably less thanabout 10 ppm of halide. Other ionic contaminants, for example phosphateor sulfate, are individually present in amounts of less than about 100ppm, preferably less than about 50 ppm, most preferably less than about10 ppm.

The methods are further illustrated by the following non-limitingexamples.

EXAMPLES

Differential scanning calorimetry (DSC) measurements were conducted byscanning the sample from 50° C. to 100° C. with a scan speed of 10°C./min. Thermal gravimetric analysis (TGA) was conducted by scanning thesample from 50° C. to 600° C. with a scan speed of 10° C./min. Ioncontent of the salts was determined by ion chromatography. Yellownessindex (YI) was determined using a Gretag McBeth color-eye 7000A usingpropalette software.

In the following examples, “MQ water” refers to water deionized andprocessed through a MilliQ® System. (MilliQ® is a trademark of MilliporeCorporation.) “TBPBr” refers to tetrabutyl phosphonium bromide.

Example 1

First, 5.00 gram (MW 302, 16.55 mmol) of perfluorobutane sulfonylfluoride (“A”) is weighed in a 100-mL 2-neck roundbottom flask, stirredwith a magnetic stirrer and refluxed therein, in an oil bath at 85° C.

Next, 0.95 grams of lithium hydroxide (LiOH) (24.83 mmol) is added anddissolved in 25 mL MQ water and slowly added to A. This is followed byletting the mixture reflux for an hour and then adding 25 mL MQ waterand stirrring. Then the undissolved residue is filtered off, andcollected in another 100-mL 2-neck roundbottom flask, and reheated in anoil bath at 85° C. once more. Next 8.43 gram TBPBr (24.83 mmol) isdissolved in 25 mL MQ water and is added slowly to the filtrate and theproduct antistatic agent is formed. After all the dissolved TBPBr isadded the mixture is stirred for another 15 minutes. Then the mixture iscooled, preferably in an ice/water bath, and then the water is decanted.Next, 100 mL of MQ water is added and stirred for 15 minutes whileheating in an oil bath at 85° C. The mixture is next cooled to roomtemperature and the product is isolated by filtration and is flushedwith 25 mL MQ water. The product is dried in a vacuum drying oven at 50°C. The theoretical yield is 9.24 grams of antistatic agent; 3.8 g wereobtained.

Example 2

First, 54.8 grams (180.837 mmol) of lithium perfluorobutane sulfonate(“Li Rimar”) is added to and dissolved in 300 mL MQ water at roomtemperature and 60.8 grams (179.062 mmol) of TBPBr is added to anddissolved in 200 mL MQ water at room temperature. The TBPBr solution isfiltered and then poured gradually into the Li Rimar salt solution whilestirring with a propeller stirrer, and the product antistatic agent isformed. After all the TBPBr is added the reaction mixture is stirred for15 minutes more. At the end of the reaction the product antistatic agentis isolated by filtration and flushed with 50 mL MQ water to remove mostimpurities. Further purification is accomplished by suspending theproduct antistatic agent in MQ water and heating it up to 80° C.,stirring it for a few minutes and cooling the mixture so that theproduct antistatic agent crystallizes again. The product antistaticagent can then be isolated by filtration and dried in a vacuum dryingoven at 50° C. The theoretical yield is 100.0 grams of antistatic agent;87.1 grams were obtained.

Example 3

First 5.00 grams (MW 302, 16.55 mmol) of perfluorobutane sulfonylfluoride (“A”) is weighed in a 100-mL 2-neck roundbottom flask, stirredwith a magnetic stirrer and refluxed in an oil bath at 85° C.

Next a 32 wt % NaOH solution is slowly added, that is 2.4 times theamount of A. That is, 39.72 mmol which corresonds with 1.58 grams ofNaOH (4.94 grams of a 32 wt % solution). The mixture is then refluxedfor an hour and then 50 mL MQ water is added and stirred untileverything was dissolved. Next 5.62 grams of TBPBr (16.55 mmol) isdissolved in 25 mL MQ water and is added slowly to this solution and theproduct antistatic agent is formed. After all the dissolved TBPBr isadded the mixture is stirred for another 15 minutes. Next the mixture iscooled down, preferably in an ice/water bath, and then the water isdecanted. Then 100 mL MQ water is added and stirred for 15 minutes whileheating it in an oil bath at 85° C. The mixture is cooled to roomtemperature and the product antistatic agent is isolated by filtrationand flushed with 25 mL MQ water. The product antistatic agent is thendried in a vacuum drying oven at 50° C. The theoretical yield is 9.24grams of antistatic agent; 5.8 grams were obtained.

Example 4

First 5.77 grams (18.083 mmol) of sodium perfluorobutane sulfonate (“NaRimar”) is added to and dissolved in 50 mL MQ water at room temperatureand 6.08 (17.906 mmol) grams of TBPBr is added to and dissolved in 20 mLMQ water at room temperature. The TBPBr solution is filtered and thenpoured gradually into the Na Rimar salt solution while stirring with astrong magnetic stirrer, and the product antistatic agent is formed.After all the TBPBr is added the reaction mixture is stirred for 15minutes more. At the end of the reaction the product antistatic agent isisolated by filtration and flushed with 50 mL MQ water to remove themost impurities. Further purification may be done by stirring theproduct antistatic agent in MQ water and heating it to 80° C., stirringit for a few minutes and cooling the mixture so that the productantistatic agent recrystallizes. The product antistatic agent is thenisolated by filtration and dried in a vacuum drying oven at 50° C. Thetheoretical yield is 10.0 grams of antistatic agent; 8.10 grams wereobtained.

Example 5

First, 5.00 grams (MW 302, 16.55 mmol) of perfluorobutane sulfonylfluoride (“A”) is weighed in a 100-mL 2-neck roundbottom flask, stirredwith a magnetic stirrer and refluxed in an oil bath at 85° C. Next, 4.46g of a 50 wt % KOH solution is slowly added to provide 2.4 equivalentsof KOH (2.23 g, 39.72 mmol) (4.46 gram of a 50 wt % solution). Themixture is refluxed for an hour and then 75 mL of ethanol/MQ (volumeratio of 3/4) is added and stirred until everything has dissolved. Next5.56 grams of TBPBr (16.38 mmol) is dissolved in 25 mL MQ water andadded slowly to this solution and the product antistatic agent isformed. After all the dissolved TBPBr is added the mixture is stirredfor another 15 minutes before cooling the mixture to room temperature.The product antistatic agent is extracted with 75 mL dichloromethane ina separatory funnel and washed 3 times with 50 mL MQ water. The organiclayer is removed under vacumm (50° C., p_(start)=475 mbar andp_(end)=125 mbar). Additional purification may be accomplished bystirring the product antistatic agent in MQ water and heating it to 80°C., stirring for a few minutes, and cooling the mixture so that theproduct antistatic agent recrystallizes. The product antistatic agent isthen isolated by filtration and dried in a vacuum drying oven at 50° C.The theoretical yield is 9.24 grams of antistatic agent; 6.04 grams wereobtained.

Comparative Example 6

First, 6.06 grams (17.9 mmol) potassium perfluorobutane sulfonate (“KRimar”) is added to and dissolved in 75 mL of an ethanol/MQ watersolution having a volume ratio of 3/4 and 6.01 grams (17.7 mmol) ofTBPBr is added to and dissolved in 25 mL MQ water at room temperature.The TBPBr solution is poured gradually into the K Rimar salt solutionwhile stirring and the product antistatic agent is formed. After all theTBPBr is added, the reaction mixture is stirred for 15 minutes more.Then the product antistatic agent is extracted with 75 mL ofdichloromethane in a separatory funnel and washed 3 times with 50 mL MQwater. The organic layer is removed under vacumm (50° C., p_(start)=475mbar and p_(end)=125 mbar). Additional purification may be accomplishedby stirring the product antistatic agent in MQ water and heating it to80° C., stirring for a few minutes, and cooling the mixture so that theproduct antistatic agent recrystallizes. The product antistatic agent isthen isolated by filtration and dried in a vacuum drying oven at 50° C.The theoretical yield is 10.0 grams of antistatic agent; 8.91 grams wereobtained.

Example 7

First, 5.00 grams (MW 302, 16.55 mmol) of A is weighed in a 100-mL2-neck roundbottom flask, stirred with a magnetic stirrer and refluxedin an oil bath at 85° C. Next, 10.98 grams (39.72 mmol) a 40 wt %tetrabutylphosphonium hydroxide is added. The mixture is then refluxedfor an hour. Then 50 mL MQ water is added and stirred for another 15minutes. The mixture is then cooled down, preferably in an ice/waterbath, and then the water is decanted. Then 100 mL MQ water is added andstirred for 15 minutes while heating it in an oil bath at 85° C. This isfollowed by cooling the mixture down to room temperature, isolating theproduct antistatic agent by filtration and flushing it with 25 mL MQwater. Next the product antistatic agent is dried in a vacuum dryingoven at 50° C. The theoretical yield herein is 9.24 grams of antistaticagent; 7.4 grams were obtained.

Table 1 provides the characterizations of the antistatic agents made viathe various synthethic routes detailed above in Examples 1-7. Thereference sample is a perfluorobutanesulfonate antistatic agent obtainedfrom Dupont under the trade name Zonyl® FASP-1. The melting point isdetermined using differential scanning calorimetry (DSC). The thermaldegradation of the the antistatic agent is determined by thermalgravimetric analysis (TGA) and is measured at the temperature whereindegradation is first detected. TABLE 1 Example No. Units 1 2 3 4 5 6 7Ref. Yield % 41.1 87.1 62.8 81.0 65.4 89.1 80.1 — Melting ° C. 77.5 75.977.6 77.4 75.1 78.0 77.3 76.7 point (DSC) TGA ° C. 387.1 386 384 388 385390 380 386 Tem- per- ature onset

As may be seen from the above Table 1, the process of Example 3 isparticularly advantageous, in that yields are high. In addition, thesynthetic steps are simple.

Table 2 shows that the antistatic agent made via the various synthethicroutes detailed in Examples 1-2 contains low ionic impurities afterwashing in water at 80° C. TABLE 2 Example No. Ion Units 1 2 3 4 5 6 7Ref. Li⁺ ppm <1 <1 <1 <1 <1 <1 <1 <1 Na⁺ ppm <2 <2 <2 <2 <2 <2 <2 <2 K⁺ppm <2 <2 <2 <2 <2 <2 <2 2.1 F⁻ ppm <2 <1 <2 <2 <1 <1 4.3 <2 Cl⁻ ppm <2<1 <2 <2 <1 <1 <2 <2 Br⁻ ppm 85 10 4.6 <2 81 <1 <4 <4 SO₄ ⁻ ppm 3.5 <1<2 <1 6.7 <2 2.8 <2 PO₄ ⁻ ppm <6 <1 <6 <1 <4 <4 <6 <6

As is known, certain byproducts commonly found in antistatic agent maybe deleterious to the properties of the compounded thermoplasticpolymers, for example polycarbonate. For example, as shown in FIG. 1,the presence of increasing amounts of bromine can result in increasingyellowing of the polycarbonate after heat aging at 130° C. for 936hours. Table 3 further shows the change in YI (Delta YI), after heataging, of polycarbonate containing the indicated amounts of ioniccontaminants. Spots were observed in the heat-aged polycarbonate, whichlikely result from potassium and sodium contamination. TABLE 3 Ionconcentration in PC (ppm) Delta YI after heat at 130° C. (Hours) Br− Li+Na+ K+ 0 65 166 569 936 0 0 0 0 0 0.7 1.1 3.3 5.6 0.1 — 0.1 <0.15 0 0.61.1 2.8 5.1 12.4 — — — 0 0.7 1.7 3.9 6.2 21.8 1.0 1.4 0 0.6 1.8 4.6 8.122.5 2.1 0.1 <0.15 0 1.1 2 5.2 9.4 24.7 — — — 0 0.9 1.8 5.8 10.5 37.0 —— — 0 1 1.9 8.7 19.1

In order to determine the effectiveness of washing the antistatic agentsof the above examples, 10.02 grams of unwashed antistatic agent producedin Example 2 above is weighed into a 150 mL beaker and 100 mL MQ wateris added. This is stirred so as to homogeneously disperse the antistaticagent in the water, and stirring is continued at room temperature for 15minutes. The antistatic agent was then filtered, dried, and tested forionic impurities.

In a second test, 10.06 grams of unwashed antistatic agent produced inExample 2 above is weighed into a 150 mL beaker and 100 mL MQ water isadded thereto. This is stirred well so that the antistatic agent ishomogeneously dispersed in the water, and stirring is continued at 80°C. for 15 minutes. At that temperature the antistatic agent of Example 2is molten, and forms an emulsion while stirring. The mixture is thencooled, and the solid is filtered, dried, and tested for ionicimpurities. Table 4 shows the yield after washing and Table 5 shows theion chromatography results. TABLE 4 Washing Units At room temp. At 80°C. Amount before washing gram 10.02 10.06 Amount of MQ water used mL 100100 Yield after washing gram 9.35 9.72 Yield after washing % 93.3 96.6

TABLE 5 Washed Ion Units Unwashed At room temp. At 80° C. Li⁺ Ppm 279 16<1 Na⁺ Ppm <2 <2 <2 K⁺ Ppm <2 <2 <2 F⁻ Ppm 1.0 <1 <1 Cl⁻ Ppm <1 <1 <1Br⁻ Ppm 2766 165 10 SO₄ ⁻ Ppm 14 2.3 <1 PO₄ ⁻ Ppm <1 <1 <1

It is possible to synthesize the antistatic agent according to all theexamples as described above. Any ionic impurities can be washed outeasily by washing the antistatic agent in water at room temperature orat 80° C.

The singular forms “a,” “an,” and “the” include plural referents unlessthe context clearly dictates otherwise. The terms “first,” “second,” andthe like, herein do not denote any order, quantity, or importance, butrather are used to distinguish one element from another. The endpointsof all ranges reciting the same characteristic are combinable andinclusive of the recited endpoint. The modifier “about” used inconnection with a quantity is inclusive of the stated value and has themeaning dictated by the context (e.g., includes the degree of errorassociated with measurement of the particular quantity). All referencesare incorporated herein by reference.

While typical embodiments have been set forth for the purpose ofillustration, the foregoing descriptions should not be deemed to be alimitation on the scope herein. Accordingly, various modifications,adaptations, and alternatives may occur to one skilled in the artwithout departing from the spirit and scope herein.

1. A method for making the phosphonium sulfonate salt of generic formula(1):

wherein each X is independently a halogen or hydrogen, provided that themolar ratio of halogen to hydrogen is greater than about 0.90; p is 0 or1 and q and r are integers of 0 to about 7 provided that q+r is lessthan 8 and that if p is not zero then r is greater than zero; and each Ris the same or different hydrocarbon radical containing 1 to about 18carbon atoms, the method comprising combining in an aqueous medium, acompound of the generic formula (2):

wherein M is Li or Na, and X, q, p, and r are as defined above, with astoichiometric excess of a compound of the generic formula (3):(R)₄P-Z  (3) wherein Z is a halogen and R is as defined above; andseparating the phosphonium sulfonate of formula (1) from the aqueousmedium.
 2. The method of claim 1 wherein X is fluorine; Z is bromine orchlorine; and three of the R groups may are the same aliphatichydrocarbon radical containing 1 to about 8 carbon atoms or aromatichydrocarbon radical containing 6 to about 12 carbon atoms, and thefourth R group is a hydrocarbon radical containing 1 to about 18 carbonatoms.
 3. The method of claim 2 wherein p is zero.
 4. The method ofclaim 1 wherein the sulfonate is perfluoromethane sulfonate,perfluoroethane sulfonate, perfluoropropane sulfonate, perfluorobutanesulfonate, perfluoropentane sulfonate, perfluorohexane sulfonate,perfluoroheptane sulfonate, perfluorooctane sulfonate, or a combinationcomprising at least one of the foregoing sulfonates; and wherein thephosphonium is tetramethyl phosphonium, tetraethyl phosphonium,tetrabutyl phosphonium, triethylmethyl phosphonium, tributylmethylphosphonium, tributylethyl phosphonium, trioctylmethyl phosphonium,trimethylbutyl phosphonium, trimethyloctyl phosphonium, trimethyllaurylphosphonium, trimethylstearyl phosphonium, triethyloctyl phosphonium andaromatic phosphonium such as tetraphenyl phosphonium, triphenylmethylphosphonium, triphenylbenzyl phosphonium, tributylbenzyl phosphonium, ora combination comprising at least one of the foregoing phosphonium. 5.The method of claim 4 wherein the sulfonate is perfluoromethanesulfonate, perfluorobutane sulfonate, perfluorohexane sulfonate,perfluoroheptane sulfonate, perfluorooctane sulfonate, or a combinationcomprising at least one of the foregoing organic sulfonate anions, andthe phosphonium is tetrabutylphosphonium.
 6. The method of claim 1wherein the molar ratio of the compound of formula (2) to the compoundof formula (3) is of about 1:1.001 to about 1:1.5.
 7. The method ofclaim 1 wherein the molar ratio of the compound of formula (2) to thecompound of formula (3) is of about 1.001:1 to about 1.5:1
 8. The methodof claim 1 wherein the aqueous medium comprises less than about 1 volumepercent of a non-aqueous medium.
 9. The method of claim 1 wherein theproduct phosphonium sulfonate precipitates from the aqueous medium. 10.A method for making the phosphonium sulfonate salt of generic formula(1):

wherein each X is independently a halogen or hydrogen, provided that themolar ratio of halogen to hydrogen is greater than about 0.90; p is 0 or1 and q and r are integers of 0 to about 7 provided that q+r is lessthan 8 and that if p is not zero then r is greater than zero; and each Ris the same or different hydrocarbon radical containing 1 to about 18carbon atoms, the method comprising combining, in an aqueous medium, acompound of the generic formula (4)

wherein X, p, q, and r have the same meanings as in formula (1), with acompound of the generic formula (5):(R)₄P—OH  (5) wherein R has the same meaning as in formula (1); and,separating the phosphonium sulfonate product of formula (1).
 11. Themethod of claim 10 wherein X is fluorine; Z is bromine or chlorine; andthree of the R groups are the same aliphatic hydrocarbon radicalcontaining 1 to about 8 carbon atoms or aromatic hydrocarbon radicalcontaining 6 to about 12 carbon atoms, and the fourth R group is ahydrocarbon radical containing 1 to about 18 carbon atoms.
 12. Themethod of claim 11, wherein p is zero.
 13. The method of claim 10wherein the sulfonate is perfluoromethane sulfonate, perfluoroethanesulfonate, perfluoropropane sulfonate, perfluorobutane sulfonate,perfluoropentane sulfonate, perfluorohexane sulfonate, perfluoroheptanesulfonate, perfluorooctane sulfonate, or a combination comprising atleast one of the foregoing sulfonates; and wherein the phosphonium istetramethyl phosphonium, tetraethyl phosphonium, tetrabutyl phosphonium,triethylmethyl phosphonium, tributylmethyl phosphonium, tributylethylphosphonium, trioctylmethyl phosphonium, trimethylbutyl phosphonium,trimethyloctyl phosphonium, trimethyllauryl phosphonium,trimethylstearyl phosphonium, triethyloctyl phosphonium and aromaticphosphoniums such as tetraphenyl phosphonium, triphenylmethylphosphonium, triphenylbenzyl phosphonium, tributylbenzyl phosphonium, ora combination comprising at least one of the foregoing phosphoniums. 14.The method of claim 13 wherein the sulfonate is perfluoromethanesulfonate, perfluorobutane sulfonate, perfluorohexane sulfonate,perfluoroheptane sulfonate, perfluorooctane sulfonate, or a combinationcomprising at least one of the foregoing organic sulfonate anions, andthe phosphonium is tetrabutylphosphonium.
 15. The method of claim 14wherein the molar ratio of the compound of formula (4) to the compoundof formula (3) is of about 1:2.01 to about 1:3.
 16. The method of claim10 wherein the aqueous medium comprises less than about 1 volume percentof a non-aqueous medium.
 17. The method of claim 10 wherein the productphosphonium sulfonate precipitates from the aqueous medium.
 18. A methodfor making the phosphonium sulfonate salt of generic formula (1):

wherein each X is independently a halogen or hydrogen, provided that themolar ratio of halogen to hydrogen is greater than about 0.90; p is 0 or1 and q and r are integers of 0 to about 7 provided that q+r is lessthan 8 and that if p is not zero then r is greater than zero; and each Ris the same or different hydrocarbon radical containing 1 to about 18carbon atoms, the method comprising combining in an aqueous mediumsodium hydroxide and/or lithium hydroxide; a compound of the genericformula (4):

wherein X, q, p, and r are as defined above; and a compound of thegeneric formula (3):(R)₄P-Z  (3) wherein Z is a halogen and R is as defined above; andseparating the phosphonium sulfonate of formula (1).
 19. The method ofclaim 18 wherein the molar ratio of the compound in formula (4) to thecompound in formula (3) is of about 1:2.01 to about 1:3.
 20. The methodof claim 18 wherein X is fluorine; Z is bromine or chlorine; and threeof the R groups are the same aliphatic hydrocarbon radical containing 1to about 8 carbon atoms or aromatic hydrocarbon radical containing 6 toabout 12 carbon atoms, and the fourth R group is a hydrocarbon radicalcontaining 1 to about 18 carbon atoms.
 21. The method of claim 18,wherein p is zero.
 22. The method of claim 18 wherein the sulfonate isperfluoromethane sulfonate, perfluoroethane sulfonate, perfluoropropanesulfonate, perfluorobutane sulfonate, perfluoropentane sulfonate,perfluorohexane sulfonate, perfluoroheptane sulfonate, perfluorooctanesulfonate, or a combination comprising at least one of the foregoingsulfonates; and wherein the phosphonium is tetramethyl phosphonium,tetraethyl phosphonium, tetrabutyl phosphonium, triethylmethylphosphonium, tributylmethyl phosphonium, tributylethyl phosphonium,trioctylmethyl phosphonium, trimethylbutyl phosphonium, trimethyloctylphosphonium, trimethyllauryl phosphonium, trimethylstearyl phosphonium,triethyloctyl phosphonium and aromatic phosphoniums such as tetraphenylphosphonium, triphenylmethyl phosphonium, triphenylbenzyl phosphonium,tributylbenzyl phosphonium, or a combination comprising at least one ofthe foregoing phosphoniums.
 23. The method of claim 22 wherein thesulfonate is perfluoromethane sulfonate, perfluorobutane sulfonate,perfluorohexane sulfonate, perfluoroheptane sulfonate, perfluorooctanesulfonate, or a combination comprising at least one of the foregoingorganic sulfonate anions, and the phosphonium is tetrabutylphosphonium.24. The method of claim 18 wherein the aqueous medium comprises lessthan about 1 volume percent of a non-aqueous medium.
 25. The method ofclaim 18 wherein the product phosphonium sulfonate precipitates from theaqueous medium.
 26. The method of claim 18 wherein the lithium and/orsodium hydroxide are added to the compound of formula (4) before thecompound of formula (5).
 27. The method of claim 26 wherein the productof the addition of the lithium hydroxide and/or sodium hydroxide is thecorresponding alkali sulfonate salt (2).
 28. The method of claim 25,further comprising isolating salt (2) prior to addition of the compoundof formula (5).